Antibodies or the T-cells?

Which arm is crucial for viral clearance & protection against #SARSCoV2? 1/
Early on in the #pandemic questions arose regarding how #SARSCoV2 is cleared during acute/primary infection & what aspects of the #adaptive immune were necessary and sufficient for protection from repeat infection 2/
Using mouse models of SARSCoV2,@BenIsraelow Rt al demonstrate that both humoral and cellular adaptive immunity contributes to viral clearance in the setting of primary infection 3/
Either convalescent mice, or mice that receive #mRNA vaccination are protected from both homologous infection & infection with a VOC, B.1.351 4/
Additionally, they conclude that protection is largely mediated by antibody response and not cellular immunity, and highlight the in vivo protective capacity of antibodies generated to both vaccine & natural infection @VirusesImmunity @SaadOmer3 5/

biorxiv.org/content/10.110…
Another study on Rhesus #Macaques finds that T cells play a role in the recovery from acute #SARSCoV2 infections, their depletion does not induce severe disease, & T cells do not account for the natural resistance of rhesus macaques to severe #COVID19 @fitterhappierAJ 6/
Neither primed CD4+ or CD8+ T cells appeared critical for immunoglobulin class switching, the development of immunological memory or protection from a second infection 7/
CD4, CD8, & CD4/8 depletion in Macaques prior and during infection did not affect disease course and only mildy attenuated viral clearance! 8/

biorxiv.org/content/10.110…
The debate continues.....Difficult to write-off the importance of T-cells. This virus is weird. Need more studies before we dump cellular arm. What we know, a harmony between the two is needed for a successful immune response! 9/

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More from @vipintukur

20 May
How the #Covid pandemic ends: The truth of the matter is that pandemics always end. And to date #vaccines have never played a significant role in ending them........ 1/statnews.com/2021/05/19/how…
......that doesn’t mean #vaccines aren’t playing a critical role this time. Far fewer people will die from #Covid19 because of them 2/
Experience from the last 4 pandemics would suggest that viruses morph from pandemic pathogens to endemic sources of disease within a year & a half or two of emerging. But all of those pandemics were flu pandemics. A different pathogen could mean we’ll see a different pattern 3/
Read 6 tweets
19 May
#Mixing vaccines: Study from #Spain indicates it is likely safe to have taken #AstraZeneca then switch to the #BNT1622b vaccine for 2nd dose—found to be “highly immunogenic & safe.” Neutralization with Pfizer for 2nd dose increased 7 folds 1/
Presence of IgG Abs was between 30 to 40 times higher in people who got the follow-up #BNT1622b shot than in a control group who only received one #AstraZeneca dose 2/

english.elpais.com/society/2021-0…
Meanwhile, the presence of #Neutralising Abs arose 7 folds after a #Pfizer dose, significantly more than the doubling effect observed after a 2nd AZ shot 3/

cp24.com/world/astrazen…
Read 5 tweets
13 May
The #Indian variant (#B16172) may be the most transmissible variant yet identified!!
This variant is 60% more transmissible than the #UK variant (#B117), & 2.6 times more transmissible than the original strain (B1)!
The #B16172 has now become the dominant variant in almost all key states on India. Data patchy (n=4480 since Jan. 2021 of which 1690 B.1.617+) but clear patterns. Data courtesy @TWenseleers
According to a new modelling study shared by @TWenseleers, the Indian VOC #B16172 would have a growth rate advantage of 7% per day over B.1.617.1 or of 10% per day relative to the UK variant B.1.1.7.
Read 5 tweets
12 May
#B16171 variant is 6.8-fold less susceptible to neutralization by sera from infection & vaccinated (Pfizer & Moderna) subjects. Despite this, most of the sera from convalescents (79%) & all from vaccinated subjects were still able to neutralize the variant biorxiv.org/content/10.110…
#Covaxin retains efficacy against #B1617: Only minimal reductions in the neutralization observed against B1617; Neutralization reduction by a factor of 1.95 & 1.8 was observed against the B1617 variant for B1 (D614G) & B117 variant, respectively. biorxiv.org/content/10.110…
#B16171 variant is highly pathogenic in hamsters than B1 (D614G) variant! B1617 demonstrates higher pathogenicity evident with reduced body weight, higher viral load in lungs & pronounced lung lesions as compared to B1 biorxiv.org/content/10.110…
Read 4 tweets
12 May
A very interesting yet a bit complicated paper. First, let’s go through the key findings of the paper:

1) the distribution of viral loads observed in asymptomatic population was indistinguishable from what has been reported in hospitalized populations 1/
2) regardless of symptomatic status, approx. 50% of individuals who test positive for #SARSCoV2 seem to be in noninfectious phases of the infection 2/ pnas.org/content/118/21…
3) just 2% of infected individuals carry 90% of the virions circulating within communities, serving as viral “supercarriers” & likely also superspreaders 3/

pnas.org/content/118/21…
Read 9 tweets
10 May
The WHO declared a coronavirus variant first identified in India, B.1.617, as a “variant of concern,” the agency’s fourth such designation wsj.com/articles/coron…
One can understand the gravity of this announcement: The Indian variant, #B1717 is now clubbed with UK #B117, SA #B1351 & Brazil’s #P1
I think this data is saying "Take B.1.617 very seriously and surge test, contact trace, support isolation of cases & contacts, ring vaccinate - NOW" @chrischirp Look, experts from UK are sounding alert on a variant originated from here! And what was our response?
Read 6 tweets

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